perceived opposition to the abortion from partners, family, and/or friends

lack of perceived social support from others

various personality traits (e.g., low self-esteem, a pessimistic outlook, low-perceived control over life)

a history of mental health problems prior to the pregnancy

feelings of stigma

perceived need for secrecy

exposure to antiabortion picketing

use of avoidance and denial coping strategies

Feelings of commitment to the pregnancy

ambivalence about the abortion decision

low perceived ability to cope with the abortion

history of prior abortion

late term abortion

By parsing of the APA summary conclusion that "adult women who have an unplanned pregnancy the relative risk of mental health problems is no greater if they have a single elective first-trimester abortion than if they deliver that pregnancy," it also appears that the APA is identifying the following as risk factors

being an adolescent (not an adult)

having more than a "single" abortion

having a non-elective, "therapeutic" abortion

(For a more comprehensive list of risk factors for psychological reactions to abortion, see here.)